Makefile and "main" repository issue

the makefile has an invalid compiler flag supplied
in the make file in the root directory (pcsx-redux)
line #23
`CXXFLAGS += -std=c++2b`
likely should be (note this works but ...)
`CXXFLAGS += -std=c++20`
once that was "removed" build worked up to...
`g++ -c -o objs/Release/src/cdrom/cdriso-cbin.o src/cdrom/cdriso-cbin.cc -I. -Isrc -Ithird_party -Ithird_party/ELFIO -Ithird_party/gl3w -Ithird_party/googletest/googletest/include -Ithird_party/imgui -Ithird_party/imgui/backends -Ithird_party/imgui/examples -Ithird_party/imgui/misc/cpp -Ithird_party/libelfin -Ithird_party/luajit/src -Ithird_party/magic_enum/include/magic_enum -Ithird_party/tracy/public -Ithird_party/zep/extensions -Ithird_party/zep/include -Ithird_party/xbyak/xbyak -g -DIMGUI_IMPL_OPENGL_LOADER_GL3W -DIMGUI_ENABLE_FREETYPE -DZEP_FEATURE_CPP_FILE_SYSTEM -DNVG_NO_STB -DPB_STATIC_API -O3 -pthread -Ithird_party/md4c/src -Ithird_party/fmt/include/ -Ithird_party/llhttp -Ithird_party/luv/src -Ithird_party/luv/deps/lua-compat-5.3/c-api -Ithird_party/multipart-parser-c -Ithird_party/ucl -Ithird_party/ucl/include -I/usr/include/capstone -I/usr/include/freetype2 -I/usr/include/libpng16 -I/usr/include/x86_64-linux-gnu -std=c++20
In file included from src/support/version.h:39,
from src/core/system.h:38,
from src/support/settings.h:43,
from src/core/psxemulator.h:47,
from src/cdrom/cdriso.h:28,
from src/cdrom/cdriso-cbin.cc:20:
src/support/uvfile.h: In member function ‘virtual bool PCSX::UvFifo::failed()’:
src/support/uvfile.h:239:60: error: ‘struct std::atomic_flag’ has no member named ‘test’
239 | virtual bool failed() final override { return m_failed.test(); }
| ^~~~
src/support/uvfile.h: In member function ‘bool PCSX::UvFifo::isConnecting()’:
src/support/uvfile.h:240:47: error: ‘struct std::atomic_flag’ has no member named ‘test’
240 | bool isConnecting() { return m_connecting.test(); }
| ^~~~
make: *** [Makefile:297: objs/Release/src/cdrom/cdriso-cbin.o] Error 1`
the main repository likely should not have such errors in the makefile and likely should build without error.
I did the recommended clone of the repository
`git clone --recursive https://github.com/grumpycoders/pcsx-redux.git`
I hope that the main repository is not the bleeding edge also... that would be kind of scary.
no source code was changed on my end and the only makefile change was to get rid of the illegal compiler flags (and the guess of what it was supposed to be).